There are primarily two types of hot water heaters used in homes and light commercial applications. The most established is hot water heaters that employ a tank to store heated water. There are several methods for adapting hot water recirculation to these tank applications. These include systems with dedicated return lines and under sink circulators or valves that use the cold supply line to the fixture to return the cooled hot water to the hot water tank. The other common type of hot water heater is the tank-less water heater which may only be a water heater or it may incorporate a boiler with a space heating element. If the unit does both water heating and space heating it is referred to as a “combi” boiler. These tank-less heaters operate based on a demand for hot water so they only activate when a hot fixture is opened and a minimum flow is established. The requirement of tank-less units limits the methods available for the incorporation of hot water recirculation. The methods available are dedicated return lines, under sink circulators, or a buffer heating tank which maintains hot water when there is no hot water demand at the fixtures. Currently available under sink valves do not allow sufficient water flow through a tank-less heater to activate the heater.
Accordingly, it is the object of this invention to provide a bypass system that can be used with either a tank-less water heater or a tank-less “combi” boiler which will maintain hot water at the fixture when applied with an under-sink bypass valve.